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arXiv 2603.19983astro-ph.EPastro-ph.SR
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DX Cha双星系统的弧：环状盘的逆行证据

The Arc in the DX Cha Circumbinary System: Evidence For a Retrograde Circumbinary Disk

School of Physics and Astronomy, University of Leeds（利兹大学物理与天文学学院）；Department of Physics and Astronomy, Bishop’s University（主教大学物理与天文学系）；Departamento de Física, Universidad de Santiago de Chile（圣地亚哥智利大学物理系）；Millennium Nucleus on Young Exoplanets and their Moons (YEMS), Chile（智利年轻系外行星及其卫星千年核）；Center for Interdisciplinary Research in Astrophysics and Space Exploration (CIRAS), Universidad de Santiago（圣地亚哥大学星际交叉研究天文与空间探索中心）；Joint ALMA Observatory（ALMA联合天文台）；European Southern Observatory（欧洲南方天文台）

Cheng Chen, Daniela Paz Iglesias, James M. Miley, C. J. Nixon

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16 pages, 8 figures
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AI总结：

研究发现DX Cha双星系统存在一个环状结构，其轨道可能与双星系统逆行，这为理解年轻恒星系统的盘状结构提供了新视角。

摘要：

DX Cha双星系统的观测揭示了一个半径为0.43 au的紧凑非对称环状结构，位于双星轨道之外。内侧盘状结构通常因双星引力作用而被清除，但假设盘状结构与双星同向旋转时，发现环状结构内侧存在空腔。然而，若盘状结构逆行，则其内边缘可更接近双星，且呈现一个或两个弧状结构，与观测一致。因此，推测DX Cha系统的盘状结构可能与双星系统逆行。结论认为，年轻恒星系统中的紧凑盘状结构是未来观测的重要目标；若盘状结构为顺行，则其性质可能与当前估计显著不同；若为逆行，则将对恒星和行星形成理论产生深远影响。

英文摘要：

Observations of the binary system DX Cha (HD 104237) reveal a compact, asymmetric ring structure with a radius of 0.43\,au. This ring is just outside the binary orbit, which has semi-major axis $a_{\rm b} = 0.22$\,au and eccentricity $e_{\rm b} = 0.665$; placing the ring at $\approx 1.2$ times the binary apocenter distance. The inner regions of circumbinary disks, $\approx 2-3\,a_{\rm b}$, are typically evacuated by strong gravitational torques from the binary, resulting in a deep gap between the binary and the disk. Accordingly, previous numerical simulations of DX Cha have found an eccentric inner cavity with almost no material inside $\approx 1$\,au, and we find similar results when making the same assumption that the circumbinary disk orbits in the same direction as the binary. However, the disk can exist much closer to the binary if it is retrograde. For DX Cha we find that the inner edge of a retrograde disk occurs at $\approx 2a_{\rm b}$, and moreover takes the form of one or two arcs, in agreement with observations. We therefore suggest that the circumbinary disk in the DX Cha system could be orbiting retrograde to the binary star system in the center. We conclude that compact circumbinary disks observed in young stellar systems are important targets for future observations; if the disks are prograde then their properties are likely to be significantly different from current estimates, while if they are retrograde then this will have profound implications for our understanding of star and planet formation.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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